Nuclear fuels stored in pools are often dried and repackaged in canisters or vessels for transport and subsequent storage, e.g., wet or dry storage. While various processes have been developed for packaging nuclear fuels into such canisters or vessels, depending on the objectives of the specific program, most processes typically involve placing the nuclear fuel in the canisters or vessels, then purging them of air by establishing a vacuum within the canisters or by pressurizing them with an inert gas. The canisters are then sealed to prevent moisture leakage into the canisters. While the canisters may be leak tested prior to sealing to ensure canister integrity at the time of closure, there is no reliable nondestructive method for verifying that the canisters remain sealed when in storage. For example, one type of nondestructive method involves weighing the canisters. Unfortunately, however, such weighing techniques are not very sensitive, and usually cannot detect minor leakage. Ultrasonic methods have also been used with some success to detect free standing water in the canisters, but again, do not provide a high degree of sensitivity. That is, such ultrasonic methods usually cannot detect minor leaks. Radiographic imaging of the canisters has also been tried, but requires extensive and involved handling processes, particularly for highly irradiated fuels. No other methods other than tapping into the canister and sampling the internal atmosphere have been investigated to any great extent.